[Make-wifi-fast] [RFC/RFT 5/5] ath9k: Count RX airtime in airtime deficit

[Toke Høiland-Jørgensen]

Toke Høiland-Jørgensen <toke at toke.dk> writes:

>> No idea. If that's possible, then track last MPDU within PPDU, so you
>> can at least fallback to _something_ when you detect a new first
>> (A-)MPDU?
>>
>> Or maybe it's impossible (i.e. not worth worrying) and HW always
>> reports last MPDU as far as status bits are concerned (regardless of
>> it being _actual_ last MPDU, i.e. it just says "ok, I'm done with this
>> PPDU").
>
> I'll try a couple of different permutations of this and see what works.
> Thanks for the ideas!

OK, so having tried all the different approaches, this seems to be the
best one. Basically, this:

	if (rs->rs_isaggr && rs->rs_firstaggr) {
		an->airtime_rx_start = rs->rs_tstamp;
	} else if (rs->rs_isaggr && !rs->rs_moreaggr && an->airtime_rx_start) {
		airtime = rs->rs_tstamp - an->airtime_rx_start;
	} else if (!rs->rs_isaggr) {
		an->airtime_rx_start = 0;
                /* keeping the previous length-based calculation here */
        }


This seems to give me RX airtime figures that correspond fairly well to
the TX airtime for running the same test in the opposite direction (I'm
running a ten-second UDP flood test and looking at the total airtime
accounted after the end of the run).

-Toke